1-phenyl-1-ethyl cation-chloride

Next, examine the structure of 1-phenyl-1-ethyl cation-chloride anion, an ion pair that is initially generated. What evidence is there for cai bon-chlorine bond cleavage Examine the electrostatic potential map for the ion pair. Which face of the cation is more available for attack How could the other enantiomer form ... 

Electrostatic potential map for i-phenyl-l-ethyl cation-chloride anion shows negatively-charged regions (in red) and positi vely-charged regions (in blue). 

The effect of an w-silyl group on the positive charge in benzyl cations can be estimated by comparing the NMR spectroscopic data for the 1 -phenyl- 1-trunethylsilylethyl cation 290 with those for the phenyl ethyl cation 78 and the cumyl cation 292 prepared under identical conditions from the corresponding chlorides with Sbl 5. The 1II and 13C NMR data for 78, 290 and 292114 measured under comparable conditions are given in Tables 10 and 11. 

Other evidence was reported by Tsukahara and collaborators from the disproportionation reaction of the radical cation of the optically active bis-viologens, (S)-1 -(1 -naphthyl ethyl)carbamoyln methyl-1 -(4-(4-( 1 -naphthyl ethyl)carbamoyl methyl-pyridinio)pyridinio-4,4 -bi pyridinium tetra chloride, NBVPR2+, 1-phenyl analog, PBVPR2 +, and 1-cyclohexylethyl analog CHBVPR2+ (see Scheme 28) [70]. 

The easiest reactions are those in which the nucleophile is the gold-activated species. Examples of this are Au(I)-catalyzed carbene and nitrene transfers (equations 142 and 143) that convert olefins into cyclopropanes or aziridines, respectively. In the carbene transfer, ethyl diazoacetate is the source of carbene and the active NHC-gold cationic catalyst is generated by chloride abstraction with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate NaBAT4. The cyclopropanation is competitive with other carbene insertions with active C H or N H bonds present in the substrate. For the aziridinations of olefins, nitrene formation is accomplished by the oxidation of sulfonamides with PhI(OAc)2 and the catalyst of choice is a gold-(I) triflate with a terpyridine ligand. 

The scheme PI 1.4.1, outlined below for the simultaneous cationic ROP and controlled free radical polymerizations, is based on the methods that were rst used and experimentally veri ed by Weimer et al. (1998). A multifunctional initiator, such as (P4-I), containing orthogonal reactive sites for CRP and ROP is used This alkoxyamine adduct, namely, benzoic acid 2-(4-chloromethyl)phenyl)-2-(2,2,6,6-tetramethyl piperidin-1-yloxy) ethyl ester, can be prepared (Puts and Sogah, 1997) by heating a solution of benzoyl peroxide and TEMPO in 4-vinylbenzyl chloride at 80°C for 24 h, followed by puri cation by chromatography. 

Hyperbranched polymers were prepared from 3-(l-chloroethyl)-ethyl benzene by cationic pol)mierization [77], and from 4-[2-(phenyl)-2-(l-2,2,6,6-tetramethylpiperidinyloxy)ethyloxy]methyl styrene [78] or / -(chloromethyl)-styrene [79] by free radical polymerization. In the cationic living polymerization, the benzylic chloride of 3-(l-chloroethyl)-ethyl benzene is activated with SnCl4 in the presence of Bu4NBr [80,81], followed by low-temperature living... 

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